THE CONTRIBUTION OF STARBURSTS AND NORMAL GALAXIES TO INFRARED LUMINOSITY FUNCTIONS AT z < 2

We present a parameterless approach to predict the shape of the infrared (IR) luminosity function (LF) at redshifts z [< or =, slant] 2. It requires no tuning and relies on only three observables: (1) the redshift evolution of the stellar mass function for star-forming galaxies, (2) the evolution...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2012-03, Vol.747 (2), p.1-6
Main Authors: Sargent, M T, BETHERMIN, M, Daddi, E, Elbaz, D
Format: Article
Language:English
Subjects:
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COSMOLOGY
Cosmology and Extra-Galactic Astrophysics
Density
GALAXIES
Infrared
INFRARED RADIATION
LUMINOSITY
MAIN SEQUENCE STARS
MASS
RED SHIFT
Sciences of the Universe
STAR EVOLUTION
Stellar mass
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Summary:We present a parameterless approach to predict the shape of the infrared (IR) luminosity function (LF) at redshifts z [< or =, slant] 2. It requires no tuning and relies on only three observables: (1) the redshift evolution of the stellar mass function for star-forming galaxies, (2) the evolution of the specific star formation rate (sSFR) of main-sequence galaxies, and (3) the double-Gaussian decomposition of the sSFR distribution at fixed stellar mass into a contribution (assumed redshift- and mass-invariant) from main-sequence and starburst activity. This self-consistent and simple framework provides a powerful tool for predicting cosmological observables: observed IR LFs are successfully matched at all z [< or =, slant] 2, suggesting a constant or only weakly redshift-dependent contribution (8%-14%) of starbursts to the SFR density. We separate the contributions of main-sequence and starburst activity to the global IR LF at all redshifts. The luminosity threshold above which the starburst component dominates the IR LF rises from log(L sub(IR)/L sub([middot in circle])) = 11.4 to 12.8 over 0 < z < 2, reflecting our assumed (1+z) super(2.8) -evolution of sSFR in main-sequence galaxies.
ISSN:2041-8205
2041-8213
DOI:10.1088/2041-8205/747/2/L31